JavaScript Map

A JavaScript Map is a collection of key-value pairs where each key and value can be of any data type. Unlike the traditional Object in JavaScript, a Map allows any data type to be used as keys, providing a more flexible and efficient alternative.

Creating a Map:
To create a Map, simply instantiate it using the Map constructor:

let myMap = new Map();

You can also initialize a Map with an array of key-value pairs:

let myMap = new Map([
['key1', 'value1'],
['key2', 'value2'],
// and so on

In the below PDF we discuss about Javascript Map in detail in simple language, Hope this will help in better understanding.


Insert Item to Map:

After you create a map, you can use the set() method to insert elements to it. For example,

// create a set
let map1 = new Map();

// insert key-value pair
map1.set('info', {name: 'Jack', age: 26});
console.log(map1); // Map {"info" => {name: "Jack", age: 26}}

Access Map Elements:

You can access Map elements using the get() method. For example,

let map1 = new Map();
map1.set('info', {name: 'Jack', age: "26"});

// access the elements of a Map
console.log(map1.get('info')); // {name: "Jack", age: "26"}

Key Features of JavaScript Map:

  • Flexible Key Types: Unlike Objects, which only allow strings or symbols as keys, Maps accept any data type as a key. This makes Maps more versatile and suitable for a wide range of use cases.
  • Order of Insertion: One of the notable features of Map is that it maintains the order of key-value pairs based on the order of insertion. This can be crucial in scenarios where the order of data matters.
  • Size Property: The Map object has a size property that provides the number of key-value pairs in the Map, making it easy to retrieve the size dynamically.
  • Iterating through Map: Maps offer built-in methods like forEach, keys, values, and entries for easy iteration through the key-value pairs. This simplifies operations like mapping, filtering, and reducing on Map objects.
  • Efficient Searching: Searching for a key in a Map is more efficient than searching for a property in an Object, especially when dealing with a large dataset. The time complexity for key lookup in a Map is O(1), providing quick access to values.

Related Question

JavaScript Map is a built-in object that allows you to store key-value pairs where each key and value can be of any data type. It provides a way to associate values with unique keys and is often used to implement dictionaries or hash maps in other programming languages.

You can create a new Map in JavaScript using the Map constructor.


You can add key-value pairs to a Map using the set method

No, a JavaScript Map cannot have duplicate keys. If you try to set a value with an existing key, it will simply overwrite the existing value associated with that key.

You can check if a key exists in a Map using the has method. It returns a boolean indicating whether the specified key is present in the Map or not.



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JavaScript WeakMap A WeakMap is

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JavaScript Boolean JavaScript Boolean is

JavaScript BigInt JavaScript BigInt represented

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